The present disclosure generally relates to small type internal combustion engines including electric starting systems and garden tool powered by such engines.
Garden tool includes riding or pushing lawnmower, hand-held or back-mounted trimmer, pruner, bush cutter, blower and chainsaw etc. Garden tool may, for example use an internal combustion engine to drive an implement, such as a rotary blade of a lawnmower, a trimming string of a trimmer, an air-generating device of a blower, and/or a saw chain of a chainsaw.
Many pieces of garden tool include engines that are manually started with a recoil starter. To start the engine, the user must manually pull a recoil starter rope.
Other pieces of garden tool include electric starting systems in which a starter motor powered by a battery pack starts the engine. Typically, such electric starting systems also include a user-actuated starter switch (e.g., a key switch or a push button). To start the engine, the user actuates the starter switch, causing the battery pack to provide starting current to the starting motor to start the engine. For example, an engine including an electric starting system in which a starter motor powered by a rechargeable battery pack and a hand-held bush cutter including the engine was disclosed in U.S. Pat. No. 5,351,565. The battery pack mounted on the engine directly in some embodiments, and disposed on a shoulder band or on a connection pipe in others embodiments, was further disclosed in U.S. Pat. No. 5,351,565. For another example, an internal combustion engine using in a pushing lawnmower comprising a starting system in which a starter motor powered by a rechargeable lithium-ion battery mounted on the engine was disclosed in U.S. Pat. No. 9,228,556 B1.
Other pieces of garden tool include engines comprising a recoil starter and an electric starting system. To start the engine, the user can select to operate the recoil starter or the electric starting system. For example, a starting apparatus for a 4-cycle gasoline engine comprising a starter motor powered by a rechargeable battery which detachably mounted on the engine and a recoil starter was disclosed in Patent EP036411861.
However, the above existing technique has the following problems. The rechargeable batteries including lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries and lithium-ion batteries, etc., used in the starting systems, are unable to meet demand of garden tools operating continuously for a long period due to several hours of charging. It requires users to regularly maintain the rechargeable batteries which fading on account of improper use or repeated charge and discharge. Especially for the most used lithium-ion batteries, it will significantly accelerate capacity fade by quick charge and discharge, long-term deep charge and discharge, high temperature environment and so on.